The present invention relates to packaging of microelectronic devices, especially the packaging of semiconductor devices.
Certain types of microelectronic devices and semiconductor chips include devices such as acoustic transducers, radio frequency emitters, radio frequency detectors or optoelectronic devices or a combination of such devices. Such devices typically require packaging which permits the passage of energy, e.g., acoustic, radio frequency or optical wavelength energy to and from devices at a face of a semiconductor chip.
Because such devices are often exposed at a front face of the microelectronic devices, they usually require protection from the elements, such as dust, other particles, contaminants or humidity. For this reason, it is advantageous to assemble the microelectronic device with a lid or other element covering the front face of such microelectronic device at an early stage of processing.
It is desirable in some types of microelectronic systems to mount chips and packaged chips having very small, i.e., chip-scale packages, to circuit panels. In some cases it is desirable to stack and interconnect chips to each other one on top of another to increase the circuit density of the assembly.
Some types of mass-produced chips also require packaging costs to be tightly controlled. Processing used to package such semiconductor chips can be performed on many chips simultaneously while the chips remain attached to each other in form of a wafer or portion of a wafer. Such “wafer-level” processing typically is performed by a sequence of processes applied to an entire wafer, after which the wafer is diced into individual chips. Advantageously, wafer-level packaging processes produce packaged chips which have the same area dimensions as the original semiconductor chips, making their interconnection compact on circuit panels and the like.